The invention relates generally to sensor systems and, more particularly, to a sensor system that is operable to adjust a physical characteristic of a sensor in response to an output of the sensor.
Various types of sensors have been used to measure the distance between two objects. In addition, these sensors have been used in various applications. For example, a turbine has a turbine blade that is disposed adjacent to a shroud. The clearance between the turbine blade and the shroud varies depending on the temperature of the turbine blade. For example, the clearance between the shroud and the turbine blade is greatest when the turbine is cold and gradually decreases as the turbine heats up. It is desirable that a gap or clearance between the turbine blade and the shroud be maintained for safe and effective operation of the turbine. A sensor may be disposed within the turbine to measure the distance between the turbine blade and the shroud. The distance may be used to direct movement of the shroud to maintain the desired displacement between the shroud and the turbine blade.
In certain applications, a capacitance probe is employed to measure the distance between two objects. Conventionally, the dimensions of the capacitance probe tip are selected to correspond to a single displacement distance between the two objects. Small probes are typically limited to small distance measurements, as a result of the signal to noise ratio. Similarly, large probes are typically limited to large distance measurements because they provide poor resolution of the distance between the two objects for small distance measurements. As a result, conventional capacitance probes may be inaccurate at displacement distances other than the displacement distance for which the probe tip was designed.
Accordingly, there is a need to provide a sensor system that would accurately measure the clearance between two objects that are displaced relative to each other over an entire range of displacement.